OLYMPIA – In early February, a trailered boat covered with thousands of quagga mussels was decontaminated at the Washington-Oregon border. The vessel’s engine and trim tabs were pressure-washed with scalding hot water at the Ridgefield Port of Entry, and the non-native mollusks were quickly destroyed.

The 24-foot pleasure boat was the 11th vessel in the past year found to be carrying quagga or zebra mussels and cleaned at Washington’s borders. Both types of mussels – few larger than a nickel – are aquatic invasive species and are prohibited in Washington.

While the tiny mussels didn’t make it into Washington, the mollusks have spread throughout a number of other states, overrunning public waterways and displacing native fish and wildlife.

“These invasive mussels have been found in several western states, and they continue to move closer to Washington every year,” said Allen Pleus, aquatic nuisance species coordinator for the Washington Department of Fish and Wildlife (WDFW). “That’s a big concern, because if they get into our waters, they will likely spread rapidly.”

Once established, quagga mussels and their relative zebra mussels can multiply quickly and threaten native fish and wildlife by consuming available food and smothering other species. The mollusks, which spread by attaching to boats or other water-based equipment, also clog water-intake systems at power plants, irrigation districts, public water suppliers, and other facilities.

Zebra and quagga mussels are native to the Caspian Sea. They entered the Great Lakes in the mid 1980s in ship ballast water, and have since spread to more than 20 states, including California and Nevada, and two Canadian provinces. Both zebra and quagga mussels are easily transported on boats and trailers because they can live out of water for up to a month.

To help prevent the spread of these invasive mollusks, WDFW is working cooperatively with the Washington State Patrol to inspect commercially hauled watercraft at the state’s Port of Entry weigh stations. WDFW enforcement officers also conduct vessel inspections during fishing seasons, while other department staff inspect boats at ramps and at events such as fishing tournaments.

Later this year, WDFW plans to operate several check stations for vessels and post signs with information about aquatic invasive species at boat launches and marinas throughout the state.

Unlawful importation of aquatic invasive species is a gross misdemeanor punishable by up to $5,000 in fines and up to a year in jail.

“Boat owners need to take responsibility for their vessels if we are going to have any success at keeping these invasive species from spreading to our waters,” Pleus said. “Recreational boaters and anglers should always carefully inspect and clean their boats and equipment before moving their vessels from one body of water to another.”

For more information on zebra and quagga mussels, as well as other aquatic invasive species, visit WDFW’s website at http://wdfw.wa.gov/ais